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<br />Henz (1974) reported the existence of fOUlteen "hot spots" of orographic storm <br />formation which accounted for the genesis of over seventy per cent of the severe <br />thunderstorms which crossed the Colorado eastern plains, These hot spots are <br />located over the foothills and higher terrain features along the Front Range in <br />areas of enhanced low level convergence. The closest hot spots to the Mason <br />Reservoir drainage basin are located over the Rampart Range near Lake <br />George about 15 miles north of Pikes Peak and along the summit of Palmer <br />Divide near Monument where it merges with the Rampart Range (see Figure 8), <br /> <br />The Lake George hot spot (coordinates B-3 in Figul'e 8) is located at an <br />elevation of about 8,500 feet with a south facing exposure. The Monument hot <br />spot (C-9) is located at about 7,200 feet about 10 to 20 miles northeast of the <br />summit of Pikes Peak with a south facing exposure cllld the Black Forest hot <br />spot (0-9) is located at about 6,000 feet with a south facing exposure, In <br />general these areas produced 3 to 5 times as many thunderstClrms als the <br />higher topography in the vicinity of PikEls P,eak, l\IIajor flooding events in the <br />Colorado Springs area have been attended by stron!J moist southeast winds <br />which are forced to flow upslope into Palmer Ridge and the hot spot region, In <br />areas to the east and south of Pikes Peak where the upslope terrain effect is <br />much less, the thunderstorm generation is below normal. Perhaps the prevailing <br />westerly winds above mountain top level interact with Pikes Peak to produce a <br />downslope inhibiting wind flow to the immediate lee of the summit. In any case, <br />severe thunderstorm formation appears to be inhibited immediately around Pikes <br />Peak, <br /> <br />The Palmer Ridge, where these hot spots are located, has long been <br />recognized as a focal point for orographic thunderstorm formation on the eastern <br />Colorado plains (Henz, 1974). Many of the t,eavy deluges associated with the <br />June 1965 floods occurred along and over this feature to the north and northeast <br />of Mason Reservoir. Immediately east of Pikes Peak is the City of Colorado <br />Springs while the Air Force Academy is located another 5 miles to the northwest. <br /> <br />Flow in the sub-cloud layer will be affected by the location of a zone of primary <br />orographic lift which stretches around Pikes Peak from the southwE!st to <br />south to northeast in theT,500 feet to 9,500 feet elevation zonl~ to where it <br />merges into Palmer Lake Divide. In this zone of primary orographic lift, air <br />flowing upslope is forced to rise about 3,000 feet in a distance, of 5 miles or <br />less. This abrupt uplift acts to assist in the condensation of moist air in tile sub- <br />cloud layer and the subsequent formation of strong thunderstorms, Colorado <br />Springs has suffered many significant flash floods from storms moving south off <br />Palmer Divide. Of additional interest are two smaller towns frequently affected <br />by flash flooding rainfalls: Manitou Springs (6,412 feet msl) to the north of Pikes <br />Peak and Cripple Creek (9,494 feet msl) to the southwest. These towns are <br />located in the zone of primary orographic lift most conducive to flash flooding <br />storms, <br /> <br />22 <br />